the round-the-world assault transport

Johan Larson · 10-11-2016, 07:51 AM

Suppose I want an aircraft that can transport a platoon of mechanized troops to the other side of the world, land without needing an airstrip, offload the troops, onload them a bit later and return to base, all without needing external assistance such as in-flight refueling.

At what TL can such a thing be built?

McAllister · 10-11-2016, 08:13 AM

Can it refuel at its destination, or are we looking at circumnavigating the globe on one tank of whatever gas it uses?

My thought is, we could build such a thing today. I'm not sure what "a platoon of mechanized troops" weighs, but a really big zeppelin with a great big solar panel across the top (maybe it swivels like a sunflower to track the sun?) should be doable. The Hindenburg-class was designed to carry 90 people and had a "useful lift" (whatever that means) of 11 tons. Hell, at this point, we could probably put a nuclear reactor in one of them. However, lighter-than-air flight probably won't beat 100mph, so this isn't exactly rapid response.

If you're looking for something faster than that, my instinct is we still COULD do it today, but A. we've never done anything like it, so I don't have much of a basis for comparison, and B. it's very different from anything we want to do. We don't need to move troops from one continent to another via plane, we need to move them to the zone of conflict from the nearest aircraft carrier.

McAllister · 10-11-2016, 08:25 AM

The Mil Mi-26 helicopter can carry 22 tons. NASA's Safe Affordable Fission Engine is 0.5 tons, and it doesn't produce nearly enough power for a Mil Mi-26 (which wants 17,000 kW), that shows we can make a fission reactor small enough to put on the chopper with room to spare for your platoon. If we wanted to make it work badly enough, I bet we could make it work.

I suspect the same is not true of TL7, but they made it to the moon, didn't they?

https://en.wikipedia.org/wiki/Mil_Mi-26
https://en.wikipedia.org/wiki/Safe_A...Fission_Engine

Johan Larson · 10-11-2016, 08:27 AM

Quote:

Originally Posted by McAllister

Can it refuel at its destination, or are we looking at circumnavigating the globe on one tank of whatever gas it uses?

No refueling. Carry along whatever you need.

weby · 10-11-2016, 08:28 AM

You are basically hitting two problems with such that you have to overcome.
Vertical take off and landing: Requires complicated machinery and a lot of power thus adds weight compared to a normal jet engine.
Endurance: requires lot of fuel and fairly low power to make the fuel last. Current long range jet airliners are about 1/3 plane 1/3 fuel and 1/3 payload and get up to 15 000 km range and you basically want at least double that range for your scenario.

It all depends on your technology assumptions. Below are few possible ways to achieve it based on different such.

TL 7+1^ with developed atomic airliners and super rocket engines. Use the atomic drive for the long range cruise and the super rocket engine for the take off and landing.

TL 9 with the incredible jet engines according to Space ships. Build a plane with a full size(1g) and a 0.1 size(0.1g) jet engine, use the full size only for take off and landing assistance and the 0.1 size for cruise and landing/takeoff. The 0.1 engine still gives you a cruise speed of 1300km/h and uses 0.5% of total mass fuel/hour, so you would need 15.5% of total mass fuel for 40 000km total range, add a little for landing+takeoff the 5% for the 1g engine and the 0.5% for the 0.1 engine for a total about 25% of loaded mass to propulsion systems+fuel to have a bit of safety margin in fuel.

TL 10^ according to UT makes it easy. Just use contra gravity, reactionless thrusters and fusion plants.

Non super science TL 10 could also likely do such with the atomic plane concept with a fusion plant and then a secondary engine with very limited fuel but high thrust for takeoff/landing. Or by using more of the total mass for power plant maybe even have the main engine be string enough to lift off and land vertically.

sir_pudding · 10-11-2016, 08:31 AM

Yeah if you willing to build steam birds, and put a reactor on an aircraft, you could probably do this at TL7, although it will take forever for your gigantic atomic helicopter to get anywhere.

The plan for the B-72 involved continuous intercontinental operations if needed.

Fred Brackin · 10-11-2016, 09:03 AM

I will start off by guesstimating that a "platoon of mechanized infantry" is 54 men and enough vehicles to carry them and their weapons. Even if said "vehicles" are skeletonized Special Ops dune buggies we're at in the area of 100,000 lbs or more. Maybe 2 or 3 times that.

https://en.wikipedia.org/wiki/Boeing...ons_.28C-17.29

A C-17 is sort of in the weight range but with 1/10th the range and what doesn't look like the rough field capacity you want either.

Experience with Ve2 tells me that no propeller driven bird at TL8 or less will do better even with a fission reactor to drive the propellers.

Zeppelins are being excluded from the start by a lack of useful speed. 12,000 miles at 100 miles per hour is 5 days. Also, the rough field thing is an issue. The only LTA I've seen with anything like rough field was a small TL8 blimp with vectored ducted fans.

Even hypothetical but ridiculously dangerous things like fission air rams at TL8- won't give you enough thrust to weight.

So yeah, TL9 or higher and what I'd really want would be a hypothetical fusion air ram.

Anaraxes · 10-11-2016, 10:01 AM

Quote:

Originally Posted by Fred Brackin

I will start off by guesstimating that a "platoon of mechanized infantry" is 54 men and enough vehicles to carry them and their weapons. Even if said "vehicles" are skeletonized Special Ops dune buggies we're at in the area of 100,000 lbs or more.

A US mech inf platoon has 4 Bradleys at 27.6 tons each, so 243K pounds just in the vehicles. Crew of three, carries six soldiers each. 3 squads of 9 (riflemen, grenadiers, squad automatic weapons). One platoon leader. So, 40 soldiers rather than 54, or another ~10K pounds of people and gear. Call it a quarter-million total for a nice roundish number, or 300K for some margin and some extra supplies beyond what the troops carry in their packs.

A Humvee is 5-6K pounds. The M1114 up-armored version is 12K. (Armor here means stopping 7.62mm rifle fire from 100 yards, fragments from a 155mm overhead airbursts, or a 12-lb mine.) 4 passengers, so you'd need 7 of those for the rifle squads, or about 10 if the vehicles need dedicated drivers. 42K - 120K pounds worth of vehicles.

McAllister · 10-11-2016, 10:25 AM

Any reason it can't be a fleet of transports? Since we have infinite money, one transport per Bradley would be a lot easier than cramming them all on the one transport.

Johan Larson · 10-11-2016, 10:35 AM

Quote:

Originally Posted by McAllister

Any reason it can't be a fleet of transports? Since we have infinite money, one transport per Bradley would be a lot easier than cramming them all on the one transport.

Sure, that's fine.

Also, full VTOL is probably not necessary. Rugged STOL that allows landing and taking off in a plowed field should be enough.

10-11-2016, 07:51 AM	#1
Johan Larson Join Date: Apr 2009 Location: Toronto, Canada	the round-the-world assault transport Suppose I want an aircraft that can transport a platoon of mechanized troops to the other side of the world, land without needing an airstrip, offload the troops, onload them a bit later and return to base, all without needing external assistance such as in-flight refueling. At what TL can such a thing be built?

10-11-2016, 08:13 AM	#2
McAllister Join Date: Jun 2013	Re: the round-the-world assault transport Can it refuel at its destination, or are we looking at circumnavigating the globe on one tank of whatever gas it uses? My thought is, we could build such a thing today. I'm not sure what "a platoon of mechanized troops" weighs, but a really big zeppelin with a great big solar panel across the top (maybe it swivels like a sunflower to track the sun?) should be doable. The Hindenburg-class was designed to carry 90 people and had a "useful lift" (whatever that means) of 11 tons. Hell, at this point, we could probably put a nuclear reactor in one of them. However, lighter-than-air flight probably won't beat 100mph, so this isn't exactly rapid response. If you're looking for something faster than that, my instinct is we still COULD do it today, but A. we've never done anything like it, so I don't have much of a basis for comparison, and B. it's very different from anything we want to do. We don't need to move troops from one continent to another via plane, we need to move them to the zone of conflict from the nearest aircraft carrier.

10-11-2016, 08:25 AM	#3
McAllister Join Date: Jun 2013	Re: the round-the-world assault transport The Mil Mi-26 helicopter can carry 22 tons. NASA's Safe Affordable Fission Engine is 0.5 tons, and it doesn't produce nearly enough power for a Mil Mi-26 (which wants 17,000 kW), that shows we can make a fission reactor small enough to put on the chopper with room to spare for your platoon. If we wanted to make it work badly enough, I bet we could make it work. I suspect the same is not true of TL7, but they made it to the moon, didn't they? https://en.wikipedia.org/wiki/Mil_Mi-26 https://en.wikipedia.org/wiki/Safe_A...Fission_Engine

10-11-2016, 08:28 AM	#5
weby Join Date: Oct 2008	Re: the round-the-world assault transport You are basically hitting two problems with such that you have to overcome. Vertical take off and landing: Requires complicated machinery and a lot of power thus adds weight compared to a normal jet engine. Endurance: requires lot of fuel and fairly low power to make the fuel last. Current long range jet airliners are about 1/3 plane 1/3 fuel and 1/3 payload and get up to 15 000 km range and you basically want at least double that range for your scenario. It all depends on your technology assumptions. Below are few possible ways to achieve it based on different such. TL 7+1^ with developed atomic airliners and super rocket engines. Use the atomic drive for the long range cruise and the super rocket engine for the take off and landing. TL 9 with the incredible jet engines according to Space ships. Build a plane with a full size(1g) and a 0.1 size(0.1g) jet engine, use the full size only for take off and landing assistance and the 0.1 size for cruise and landing/takeoff. The 0.1 engine still gives you a cruise speed of 1300km/h and uses 0.5% of total mass fuel/hour, so you would need 15.5% of total mass fuel for 40 000km total range, add a little for landing+takeoff the 5% for the 1g engine and the 0.5% for the 0.1 engine for a total about 25% of loaded mass to propulsion systems+fuel to have a bit of safety margin in fuel. TL 10^ according to UT makes it easy. Just use contra gravity, reactionless thrusters and fusion plants. Non super science TL 10 could also likely do such with the atomic plane concept with a fusion plant and then a secondary engine with very limited fuel but high thrust for takeoff/landing. Or by using more of the total mass for power plant maybe even have the main engine be string enough to lift off and land vertically. __________________ -- GURPS spaceship unofficial errata and thoughts: https://gsuc.roto.nu/

10-11-2016, 08:31 AM	#6
sir_pudding Wielder of Smart Pants Join Date: Aug 2004 Location: Ventura CA	Re: the round-the-world assault transport Yeah if you willing to build steam birds, and put a reactor on an aircraft, you could probably do this at TL7, although it will take forever for your gigantic atomic helicopter to get anywhere. The plan for the B-72 involved continuous intercontinental operations if needed. Last edited by sir_pudding; 10-11-2016 at 08:35 AM.

10-11-2016, 09:03 AM	#7
Fred Brackin Join Date: Aug 2007	Re: the round-the-world assault transport I will start off by guesstimating that a "platoon of mechanized infantry" is 54 men and enough vehicles to carry them and their weapons. Even if said "vehicles" are skeletonized Special Ops dune buggies we're at in the area of 100,000 lbs or more. Maybe 2 or 3 times that. https://en.wikipedia.org/wiki/Boeing...ons_.28C-17.29 A C-17 is sort of in the weight range but with 1/10th the range and what doesn't look like the rough field capacity you want either. Experience with Ve2 tells me that no propeller driven bird at TL8 or less will do better even with a fission reactor to drive the propellers. Zeppelins are being excluded from the start by a lack of useful speed. 12,000 miles at 100 miles per hour is 5 days. Also, the rough field thing is an issue. The only LTA I've seen with anything like rough field was a small TL8 blimp with vectored ducted fans. Even hypothetical but ridiculously dangerous things like fission air rams at TL8- won't give you enough thrust to weight. So yeah, TL9 or higher and what I'd really want would be a hypothetical fusion air ram. __________________ Fred Brackin

10-11-2016, 10:25 AM	#9
McAllister Join Date: Jun 2013	Re: the round-the-world assault transport Any reason it can't be a fleet of transports? Since we have infinite money, one transport per Bradley would be a lot easier than cramming them all on the one transport.